The present invention is suited to application to a storage system having a snapshot function and a journal function.
Storage systems storing data for business information systems are responsible for playing the role of data protection in the related art. As a result of the requirements of data protection, in the field of storage systems, a snapshot function and journal function have been proposed so that a replication that is a copy of data is acquired without stopping the business information system, and in the event that an accident or operation error occurs, data can be immediately restored from the replication so that a certain past state of operation is returned to (in the following, this process is referred to as “recovery”).
A snapshot function is a function for making a replication by copying data of a storage region to a separate storage region at the time a storage system receives a snapshot instruction from a host computer. At the storage system, it is possible to intermittently acquire replicated data by executing a snapshot function periodically. Further, in the event of using a snapshot function, it is possible for the user to perform recovery at the point the snapshot is acquired.
A journal function is a function for producing and saving a journal from control information relating to writing and write target data when a storage system receives a write request from a host computer. Japanese Patent Laid-open Publication No. 2005-18738 discloses recovery processing executed at a point other than a point of producing a snapshot by writing data for a write target within a journal into a snapshot acquired by a snapshot function. This means that recovery is possible at a large number of points from a small number of snapshots by combining a journal function and a snapshot function.
However, the storage system of Japanese Patent Laid-open Publication No. 2005-18738 has to guarantee a physical storage region for writing data for all of the recovery targets in order to implement recovery up to the point designated by the host computer during execution of the recovery processing to the point designated by the host computer and a massive storage region is therefore required as a result.
Further, in order to execute recovery processing directly up to the point designated by the host computer for the snapshot while executing recovery to a point specified by the host computer, there is a problem in that the storage system of patent document 1 discards the snapshot, and is therefore not capable of executing recovery processing from the same snapshot.